feat(cli): shell completion for commands, flags, and entity names (#244)

* feat(completion): complete known argument values

* fix(completion): hide Commander-hidden subcommands from completions

Replace the `__`-prefix name heuristic with Commander's `_hidden` flag so
internal subcommands registered with { hidden: true } (e.g. `mcp serve-internal`)
are excluded from completions, mirroring `ktx --help`.

* test: cover wiki and sl read command routing

* test: cover raw wiki and sl reads

* feat: add wiki read command

* feat: add sl read command

* feat: complete read command entity names

* docs: document wiki and sl read commands

* test: include read commands in command tree

* feat(sl): read and validate unique sources by name

* feat(sl): make read and validate connection id optional

* fix(completion): dedupe semantic source names

* docs(sl): document connection-optional read and validate

* fix(sl): require connection id for query command

* docs(sl): clarify query connection requirement

* fix(completion): don't resolve option values as subcommands

resolveCommand skipped flag tokens but not the value consumed by a
value-taking option in the `--flag value` form, so a connection id like
`query` was matched as the `sl query` subcommand and yielded no `sl`
completions. Track value-taking options and skip their consumed value
before matching subcommands.

* test(telemetry): assert first-run notice via TELEMETRY_NOTICE constant

CI (which tests this branch merged with main) failed because #243 changed
the first-run notice wording in identity.ts (dropped "anonymous") but left
this test grepping for the old literal 'ktx collects anonymous usage data',
so indexOf returned -1. Assert against the exported TELEMETRY_NOTICE
constant instead so the test tracks the source of truth and cannot drift
when the notice text changes again.

docs-site/content/docs/cli-reference/ktx-completion.mdx

@@ -0,0 +1,86 @@
+---
+title: "ktx completion"
+description: "Print a shell completion script for tab completion."
+---
+
+Print a shell completion script for **ktx**. Once installed, pressing <kbd>Tab</kbd>
+completes commands, subcommands, and flags, and - inside a **ktx** project - the
+names of things that already exist: semantic-layer source names for
+`ktx sl read` and `ktx sl validate`, wiki page keys for `ktx wiki read`, and
+configured connection ids for `ktx connection test`, `ktx ingest`, and
+`ktx sql`. This saves you from remembering exact source, page, or connection
+names.
+
+## Command signature
+
+```bash
+ktx completion <shell>
+```
+
+`<shell>` must be `zsh` or `bash`. The command writes the script to stdout; it
+does not modify any files. Enable completion by evaluating the script in your
+shell startup file.
+
+## Installation
+
+Add the matching line to your shell startup file, then restart your shell (or
+`source` the file). `ktx` must be on your `PATH`.
+
+```bash
+# zsh — add to ~/.zshrc
+eval "$(ktx completion zsh)"
+```
+
+```bash
+# bash — add to ~/.bashrc
+eval "$(ktx completion bash)"
+```
+
+To try it for the current session only, run the same `eval` line directly in
+your terminal.
+
+## What gets completed
+
+| Position | Completions |
+|----------|-------------|
+| `ktx <Tab>` | Top-level commands (`setup`, `sl`, `wiki`, `ingest`, …) |
+| `ktx sl <Tab>` | The `read` / `validate` / `query` subcommands |
+| `ktx sl read <Tab>` | Existing semantic-layer source names |
+| `ktx sl validate <Tab>` | Existing semantic-layer source names |
+| `ktx wiki <Tab>` | The `read` subcommand |
+| `ktx wiki read <Tab>` | Existing wiki page keys |
+| `ktx connection test <Tab>` | Configured connection ids |
+| `ktx ingest <Tab>` | Configured connection ids |
+| `ktx sql --connection <Tab>` | Configured connection ids |
+| `ktx completion <Tab>` | `zsh` or `bash` |
+| `ktx <command> --<Tab>` | The command's flags and inherited global flags |
+| `ktx sl --output <Tab>` | An option's allowed values (here `pretty`, `plain`, `json`) |
+| `ktx sl --connection-id <Tab>` | Configured connection ids |
+
+Source names, wiki page keys, and connection ids are read from the **ktx**
+project resolved from your current directory (or `--project-dir` /
+`KTX_PROJECT_DIR`). Outside a **ktx** project, completion still suggests
+commands and flags but no project entities. Bare `ktx sl <Tab>` and
+`ktx wiki <Tab>` complete subcommands instead of entity names because their
+positional arguments are free-text search queries.
+
+## Examples
+
+```bash
+# Print the zsh completion script
+ktx completion zsh
+
+# Print the bash completion script
+ktx completion bash
+
+# Install for zsh
+echo 'eval "$(ktx completion zsh)"' >> ~/.zshrc
+```
+
+## Common errors
+
+| Error | Cause | Recovery |
+|-------|-------|----------|
+| `error: command-argument value '<name>' is invalid for argument 'shell'. Allowed choices are zsh, bash.` | A shell other than `zsh` or `bash` was requested | Re-run with `ktx completion zsh` or `ktx completion bash` |
+| Tab completion does nothing | The script was not evaluated, or `ktx` is not on `PATH` | Confirm the `eval` line is in your startup file, restart the shell, and verify `ktx --version` runs |
+| Source, page, or connection names are missing | The current directory is not inside a **ktx** project | Run from the project directory, or pass `--project-dir`, or set `KTX_PROJECT_DIR` |